Welding mechanism



Sept. 21, 1948.

C. F. LEATHERS WELDING MECHANISM Filed July 17, 1944 8 Sheets-Sheet lINVENTOR. 6%esfer 2 /841 1 Sept. 21, 1948. c. F. LEATHERS WELDINGMECHANISM Filed July 17, 1944 8 Sheets-Sheet 2 INVENTOR. C'Xagfer' 77/84 5/}:112

P 1948. c; F. LEATHERS WELDING MECHANISM 8 Sheets-Sheet 3 Filed July 17,1944 I IN VEN TOR.

8 Sheets-Sheet 4 I )kzsfer BY W C. F. LEATHERS WELDING MECHANISM Sept.21, 1948.

Filed July 17, 1944 P 1948. c. F. LEATHERS WELDING MECHANISM 8Sheets-Sheet 5 Filed July 17, 1944 1N VEN TOR.

Sept. 1948. c. F. LEATHERS WELDING MECHANISM 8 Sheets-Sheet 6 Filed July17, 1944 flllilllrllll I llllnxl f f 2 :1 z ..\l..|||ll I 1 llllwlfINVENTOR.

' 6&65229' Z'Zeaiiem P 1943- c. F. LEATHERS WELDING MECHANISM Filed July17, 1944 8 Sheets-Sheet 7 726326., /eqzzelzs.

M 44/ m M @4 m .9 0 2 l 4 a y u Sept. 21, 1948. c. F. LEATHERS WELDINGMECHANISM Filed July 17, 1944 8 Sheets-Sheet 8 Patented Sept. 21, 1948UNITED STATES PATENT OFFICE WELDING MECHANISM Chester F. Leathers,Detroit, Mich.

Application July 17, 1944, Serial No. 545,322

2 Claims.

welding devices and in certain respects .is particularly directed to theprovision Of an improved system utilizing storage batteries as a sourceof current for making welds. In other respects the invention isparticularly directed to the provision of improved elements of weldingsystems whichhave a more general application.

Principal objects of the present invention are to provide a'rela-tivelysimple economically manufactured, readily operated and maintainedresistance Welding system utilizing electric storage batteries as asource of current for making successive welds; to provide such a systemwhich as a whole is transportable so that it may be-readily moved tovarious parts of a welding shop; to provide such a system comprisinggenerally a power unit and one or more welding .guns, the power unit.being transportable as aforesaid, and the gun being of the portabletype which is adjustably carried by the power unit; to provide such asystem wherein the hanger structure for connecting the gun to the powerunit also serves as a conductor of electricity for the gun; to providesuch a system wherein the transportable-unitalso carries its own batterycharging mechanism, .and wherein the capacity of the unit is sufiicientto handle a relatively large number of welds "without requiring are-charging or alternatively in which the charging mechanism operatesautomatically to maintain a predetermined charge on the batteries; andto in general provide .a completely self-contained readily transportableWelder.

Further objects of the present invention are to provide a welderhavingan improvedframe struc ture, structural elements whereof areutilized as reservoirs to accommodate fluids, such as air, used in.performing certain of the control operations.

Further objects of the present invention are to provide improvedcontactor mechanism for controlling the how of current between one ormore welding guns and an associated source of power comprisingpreferably, but not necessarily, one or more electric storagebatteries;to provide such a contactor which, basically, employs carbon pileelements, disposed to, be separated to interrupt the flow of current,and disposed to be pressed together to complete the circuit through thecontactor; to provide such a structure embodying improved means forenabling air pressures of commercial values to act through a relativelysmall air operated ram and apply desired pressures between the carbonpile elements; and, to,

provide such structures embodying improved means interposed between thecarbon pile elements and the air operated ram for multiplying thepressure developed by the ram.

Further objects of the present invention are to provide improved weldingguns, which are-extremely light in weight and which are consequentlyextremely easy to manipulate; to provide such constructions employinggenerally a frame structure and a pair of relatively movable electrodes,the frame structure being constituted primarily by tubular elements; toprovide such structures, of the portable type, employing improved meansfor providing difierent ranges of movement between the electrodes, tothereby afford .a working range and aretracting range.

Other and more detailed objects of the invention appear in the followingdescription and in the appended claims.

In the accompanying drawings, which illustrate preferred embodiments ofthe invention, and throughout the several views of which, correspondingreference characters are used to designate corresponding parts;

Figure 1 is a view in elevation of a preferred embodiment of theinvention.

Figure 2 is a fragmentary view in side elevation showing the truck unitin a difierent position.

Figure 3 is a diagrammatic view illustratingthe adaptability of thepresent welder.

Figure 4 is a view in side elevation of the improved pewer unit.

Fig. 5 is a fragmentary plan view showing the connection between theimproved bus-bar and hanger structure and the power unit.

Figure 6 is a fragmentary plan view of the improved bus-bar and hangerstructure.

Figure '7 is a diagrammatic view of the fluid control circuits.

Figure 8 is a viewyin side elevation, partly in centrallongitudinalsection, of the improved welding gun.

Figure 8A is a fragmentary view in horizontal section taken along theline -8A8A of Fig. 8.

Figure 9 is a plan view of the gun of Figure 8, takenalong the line 9-9of Figure 3 Figure 1.0 is a bottom plan view of the improved contactor.

Figure 11 is a view in vertical section, taken along the line I l-I I ofFigure 10 and;

Figure 12 is a fragmentary view, taken along the line. i 2-42 of Figure9.

It will be appreciated from a complete understanding of the presentinvention, that the improvements thereof may be embodied in welders ofwidely varying capacities and intended for widely differing types ofservice; that in certain of their broader aspects, many features of thepresent complete system may be utilized independently of other features;and that the present improvements may be embodied in widely differingstructural forms. The present disclosure, therefore, of a particularstructural embodiment is to be regarded in an illustrative and not in alimiting sense.

Referring first to Figure l, the system as a whole comprises thehereinafter described improved power unit 20, and the improved weldinggun 22, which is of the portable pinch-gun type, and which iselectrically and mechanically connected to the power unit through theimproved bus-bar and hanger structure 24.

An important feature of the present invention resides in providing asubstantially or entirely self-contained, readily transportable weldingsystem. To accomplish this, the entire system is provided with meanswhich enable it to be transported at will from place to place in theassociated shop or factory. As shown, the transport unit comprises anindustrial truck 26 of a commercially available type. Truck 26 comprisesa usual body structure 28, a pair of rear wheels 36, a pair of swiveledintermediate wheels 32, and a single dirigible and driving front wheel34, the power unit for which may be housed within the enclosure 36. Thetruck is provided with a usual manually gripped handle 38 which may beactuated to steer the front wheel 34, and to releasably lock it ineither a straight ahead position or a position turned at 90 degreestherefrom. The handle 38 may be provided with a control switch indicatedat 40, which controls the starting, stopping and reversing of theassociated drive unit 36. Thus, it will be understood that the truck maybe started and steered manually through any desired course. In addition,by turning the front wheel 34 to its 90 degree position, the drive unitmay be started, and cause the truck 26 to revolve in a circle about acenter which lies between the rear wheels 30, which operation is showndiagrammatically in Figur 3. It is usually found that it is unnecessaryto anchor the truck to accomplish this operation. If desired, aretractable anchor post 42 may be provided, to establish a center ofrotation for the truck. It will be understood that during such rotationof the truck, the intermediate Wheels 32 occupy positions as indicatedin Figure 1, which swiveling is permitted by the nature of theirconnection to the truck.

In accordance with the present invention, the power unit 29 and theparts carried thereby are adjustable relative to the truck 26. Moreparticularly, and as is indicated in Figure 4, the truck body carries alower annular ball race 3|, and the unit 20 carries a cooperating upperball race 33. An annular series of ball bearings 29 is interposedbetween the race 3| and 33, and enables unit 20 to be freely rotatedrelative to the truck 26. Thus, for each truck position, the gun 22 maybe moved to and used in any position around the circumference of acircle having a radius somewhat in excess of the length of the bus-barand hanger unit 24. As an example of the freedom which this affords, itwill be noted from Figure 3, that, without moving the truck 26, th gun22 may serve two or more work stations a, b, and c on the turntable typework holder F. Alternatively, of course, the turntable F may b rotatedto bring the successive stations to the gun. This portability of thepower unit enables it to carry various capacity power circuits.

types of welding elements, such as pedestal assemblies and the like, aswell as the illustrated portable gun 22.

Referring particularly to Figur 1, it will be noticed that the bus-barand hanger structure 24 is pivotally connected to the power unit 20 at43. Unit 24 and its counterweights 44 may thus swing in a vertical planeto accommodate the height of the work W. Gun 22 is mechanicallysupported from unit 24 by means of the cable 46, which is trained overan idler pulley 48, and extends to a spring loaded reel 50. Gun 22 maythus be moved to different vertical positions relative to the hangerstructure 24 and may also be universally moved with respect to unit 24.

As is further illustrated in Figure 2, it is preferred to provide thetruck 26 with a usual charging unit 60, which may be conventionallyconnected by means not shown to the hereinafter described batterieswithin the unit 20, so as to deliver charging current thereto. Charger60 may be connected to a suitable source of charging current by means ofthe relatively light cable 62. As aforesaid, it is preferred to utilizea bank of batteries having sufficient capacity to handle a rela tivelylarge number of welds without requiring a re-charging operation of thebatteries. In general, however, it is found that lighting and lowcapacity power circuits are available at the various points in the shopat which it is desired to use the welder. Since the time required forthe making of each weld is usually only a very minor fraction of theinterval between successive welds, it will be understood that thebatteries may be continuously maintained at full charge by drawing onlya very small amount of power from the charging connection 62. The unitmay therefore be served. from the aforementioned lighting or low It isof course preferred to provide the charger 60 with the usual automaticcontrol elements which automatically serve to start and stop the chargerand maintain the batteries at a desired full charge.

Referring more particularly to Figures 4 and 5, the unit 20 is providedwith a generally rectangular frame structure comprising a pair of rearcorner posts 10 and a similar pair of front corner posts 12. All fourcorner posts may be and preferably are of rectangular box section. Attheir lower ends, all corner posts 10 and 12 may be and preferably arewelded to the base plate 35. Each rear corner post 10 and itscorresponding front post "are interconnected by a horizontal top member14, also of box section. The upper ends of the front posts 12 areinterconnected by an angle member 16, the respectively opposite ends ofwhich are welded or otherwise permanently secured to the correspondingposts at points adjacent the inner edges thereof. A similar angle memberinterconnects the upper ends of the rear posts 10.

The four faces of the unit 20 are preferably provided with removablecovers such as 80, which, upon removal, afford ready access to theinterior of the frame structure, to permit inspection or repair of theapparatus contained therein.

It will be appreciated, that as thus far described, the present framestructure is applicable to a wide variety of different welders,independently of the source of power utilized in connection therewith. Afurther feature of the present frame structure which is of genericutility, resides in utilizing the hollow frame elements as reservoirs orstorage spaces for fluids, such as air, which are required in connectionwith the operation of the welder.

mam-ma:-

Inrthe' presenttinstance; air.,-at.differentzpressures and ar.e:closeclthereby. Thezupper iends ofrpost's.-

122' are: closedi-by associated coverplates 84; which may 'beiweldecl'inplace thereon; Thus; itwill be understood that the present. framestructurer affords four" reservoirs, two" of which;are-constituted-bythe respective frontiposts '12-. Anadditional 1reservoir is constituted: by one; rear" post I0 and itsassociatedicrossmember I41 Theotherreservoir is constitutedrby. theremaining; members!!! and 'M The'fluid circuits. associated with? thesereservoirs are-shown in' Figure '7; and: aredescribed hereinafter;

Since the present system" is designed tocuse batiteries as-a source. of.power; the ab-ovedescribed; frame structure is arranged" to accommodateseries ofelectric storage-batteries 86- which',. as shown; are arrangedin; upper and lower: tiers. Thertiersof batteries are carried-onassociated? she1ves-88-, which; in turn, are supportedby angle members90. Onepair: of angle members 90, for. each shelf-Sans provided;Each-angle member 90 is-zweldedto one-face of its corresponding front:and rearposts 'IOiandaTZ.

Relatively heavy and preferably water cooled connectors 94' are providedto interconnect the batteries of the respective banks. These'connectors-inuturnare electrically connected to vertically' extending positive andnegative'bus-bars' Miami 98, by means of terminals I001". The'lowerterminals I09." are also connected; to, but? are" insulated'fromtheframe members by'means of" supporting angle brackets I02and-insulators I63: The lower terminals I00" thus afford mechanicaltsupport for the bus-bars-96-and 99. Therear on positive bus-bars 96 areelectrically: connected'by means. of a usual-flexible shunt I I0;tooneterminal-I I2 of the hereinafter described contactori I I4? Theother terminal I=I6- of'the=contactor is elec+ trically; connected, bymeans of: a similar 'flexible shunt H8; to a heavy terminal. I;whichisse= cured, by studs- I22.to one of the combined hanger! and bus'bar members I24. which make" up the previously mentionedunit 24: Thenegativeibus bars 98 are lconnected by means ofa=flexibleshunt I26- to.a bracket I28:which in: turnisxsecured to? the other combined: bus-bar.andrhanger member Comin now to the pivotal connection between: thebus-barand hanger unit 24 and:the:fr.ame,.arelatively heavy bracket I32"is secured to thev frame: at'the top-thereof and isprovided with; threespaced pairs of 'bearingcbosses I34; I315;v and;

I38.- These pairs of' bearing bosses-support bear--- ing pins I 40; I42,andalMt Pin.I42:rotatably:supports. the inner ends of the.- previouslymentioned" bus-bars- I-24 and I30; which are insulated from eaohtother.by means of" the insulatingrdiscs I46; and an. insulatin sleeve I49.Pins. Mlliand I44 support reinforcing; struts l50 which converge towardsandare connected. to but insulated-fromt the. respective sides of. thebus-bar unit: 24'; 318 1 indicated-at -I52.(Figure.1)

The struts I50 are also?providedxwithithreaded ends ofa bus bars I24 andI30;

6* bores. I54 through: whichzcorresponding; counterfweiglitt armsy I56,associated with: the previously; mentioncdicounterweights 44'; arethreaded. As: will be appreciated, counterweights-MI- substantially;balance atheiweig'htuof" the :unit; 2,4;pthe gun 22; and? associated;parts which are carried by" these elements; Virtually noeffort ISithGIBfOIG required: iwswinging the unit: 24 in the aforesaid" verticalplane; Similar1y,-".it will be understood thattthe' spring: biased: reel50? substantially, bal:-

ances the'rweightrofr the gun 22'soi that virtually no effort? isinvolved in manipulating the:gun; relative to its h anger;

It will be appreciated that in the broader;

aspects-0f the invention the welding current may" be regulated invarious ways such for example as by 'varying the minimum resistance of:the'herein; after: described con'tactor H4 by regulating thecontrolvoltage of tliecharger and by arranging; the: batteries in-variousseries and parallelar rangements; Ar' preferred way of obtaining 'a; desiredrange of adjustment of the. welding currenti comprisesaarheost'at-like arrangement for. vary ing: thGIBSiStitIlCBOf'. thebus-bar I30, which is; consequently made in. two slightly spacedsections at anclb, having a gap c therebetween-(Figure 6). A bus-barIBII havingsa resistance in. excess of that of" the preferablycopperbusi-bar I30; is-secured-to section-a of -bus bar I30. by StudszI62; andfis secured: to section b of: bus-bar I 30 by" one or more studsI64; Spacers I 66 serve to" maintain. bus-bar I- in slightly spacedrelation tobus-bar I30? A slide h'aving. upper andilower plates;Ififisand I in .may be releasably clamped to bus bars I30 and I60; bymeansof azstud I12 which: is provided withv a. controlhandle I142 Whenclamped, intheposition shownin Figure" 6, plates" I 68 and: H0electrically connect section"- b oftbusmar I30 and bus-bar 50.. Underthese conditions th'e'connection betweensections a and b of: bus-bar I30includes substantially the full length of bus bar I60, so that theresistance of thecircuitis at a-maximum. As'plates I68-and III): aremoved. tothe left as-viewed inFigure -6,

' lessand-less of bus-bar Iiillris required to be traversed'by thecurrent, so that the'resistanceof the circuit is progressively reduced.When plates I68 and II0'-reach their lefthand limit position,determinedby the engagement of stud. I'I2with the lefthand spacerIii-6;,these plates directly'overlieboth' of -seotio'n's-a and b and sodirectly interconnectthese low resistance' bus bar sections, therebyproviding a minimum circuit resistance.

Referringnow-to Figuresl; 8-,- 8A; 9,and12; the improvedrwelding. gun22*is illustrated as being of= the :pinch-guntype; and is-provided withupper and lower: welding. points I 9.0 and I82, which may be of'usualWatercooledconstruction;- The lower point I82 is electrically connectedto an adapter: I84;v which in turn is electrically connected through aflexible water cooled. cable I86, t0 an associated. terminal I88. Theupperpoint I is electrically connected to a movable member I92 which inturn is connected; by means of a usual flexible shunt I94; to aterminalI96. Terminals I 88anrd I 96 are connected-respectively by bolt 200 toterminals I9! and I99 which are associated respectively with-cablesI9'0and' IfII. Cables I and I91 are" connected respectively'to the outerInsulating discs 2021: and insulating:- sleeve 203* electrically isolateterminals" I88:- I 91lfrom terminals I 9-5-I 991 The nut 204 associatediwith stud 20.0" is preferably tightened. dowm sufficiently: to prevent.pivotal movement :between vthezgunzandxthe flexible cables 198 duringnormal operation, all pivotal movements of the gun relative to thehanger unit 24 being accommodated by the relatively free flexibility ofthe cables 198, l 91.

A feature of the present construction resides in providing an extremelylight but very rigid frame structure for the gun. More particularly, theframework of the gun is constituted primarily by an upper plate 218, thesingle relatively large tubular member 212, a pair of tubular members214, and interconnecting tubular members 216, 218, 228, and 222. All ofthe connections between the just mentioned tubular members and theplate-like member 2 I 8 may be and preferably are eifected by welding,as indicated at 224. It will be noticed that the previously mentionedelectric cable 186 is housed within the larger tubular member 212 and itwill be understood that although all of the elements 218 through 222 arein electrically continuous relation to each other, substantially all ofthe welding current passes through the cable 186 rather than throughelements 218 through 222. For cooling, cable 186 is provided with atubular core 181. Water introduced to the core at the inlet 189 returnsthrough the mesh-like cable body and is exhausted through the outlet 19I.

Referring particularly to Figure 9, it will be noted that the upperplate 218 is provided with a relatively large aperture 238, throughwhich the bracket 198 passes in spaced relation.

As will be appreciated, the lower welding point 182 is fixed relative tothe frame of the gun and the clamping of the work is accomplished bymoving the upper point 188 toward the lower point 182. To accomplishthis, the previously mentioned bracket 192 is rigidly secured to but isinsulated from the movable cylinder 248 of an air operated ram 242, bymeans of a stud 244, and insulating elements 246, 248, and 250.

Cylinder 248 is slidable Within an outer cylinder 252, which is securedto the handle casting 254 by means of vertically spaced pairs of studs256. The handle casting 254 is rigidly secured to the plate member 218by studs 258. In addition, cylinder 252 is directly secured to plate 218by studs 268. Cylinder 242 and the handle casting are insulated fromplate 218 by insulator 259 and washers such as 261 and sleeves such as263 associated with the various connecting studs.

A piston 262, which is movable with respect to the movable cylinder 248,but is fixed with respect to the outer cylinder 252, is rigidly securedby a nut 284 to the lower end of a piston rod 268, the upper end whereofis rigidly secured to and forms a closure for the upper end of the outercylinder 252, by a nut 268. The upper end of the moving cylinder 248 isclosed by a plate 2'18, which is sealed with respect to the piston rod266 and the outer cylinder 252 by means of cup washers 2'12 and 214.Similar cup washers 2'16 seal the piston 282 with respect to the movingcylinder 248.

The piston rod 266 is provided with an axially extending passage 288,one end whereof communicates with the air line 282 and the other endwhereof communicates with the chamber space 284 which lies betweenpiston 262 and the lower end of the movable cyilnder. A lateral passage284 interconnects passage 288 with the chamber space 286 which liesbetween the upper end of the movable cylinder 248 and the upper end ofthe outer cylinder 252. The other air line 288 communicates throughpiston passages 298 and 292 with the cylinder space 294, which lies be-8 tween piston 282 and the upper end of the movable cylinder 248.

As is described below, in connection with Figure 7, line 288 iscontinuously supplied with air at a relatively low pressure and line'282 is normally connected to exhaust. Accordingly, the chamber space294 is continuously subjected to the above-mentioned relatively low airpressure and which pressure is enabled to maintain cylinder 248 in itsillustrated elevated position. When it is desired to make a weld, line282 is connected to a source of superior air pressure which, whenadmitted to chamber spaces 284 and 286, is enabled to overcome thepressure in chamber 294, and cause cylinder 248 to move downwardly intoclamping engagement with the work. Upon release of the just-mentionedsuperior pressure, the pressure in chamber 294 is enabled to separatethe welding points, the degree of separation being controlled by acontrol member 388.

Control member 388 is in the form of a stepped post, having a pluralityof shoulders 382 spaced therealong. Post 388, which is freely slidablein a bore 384 provided in the handle casting, passes freely in spacedrelation through an opening in plate 218 and is threaded at its lowerend 386,

into a threaded opening in the bracket 192.

Bore 384 communicates with a transverse bore 388, which slidablyreceives a detent 318 (Fig. 12).

Detent 318 is provided with a, nose 312 which is disposed to haveinterlocking engagement with any of the shoulders 382, and is urged tothe left as viewed in Figure 12 by means of a compression spring 314which is seated between a shoulder formed on the detent and a nut 316which closes the end of bore 388.

The outer and reduced end 318 of detent 318 carries a releasing trigger328 which is conveniently accessible to the hand of the operator.

-. As to operation, it will be appreciated that the gun parts may beregarded as normally occupying the fully opened position shown in Figure8, in which position detent 318 engages one or the other of the lowershoulders 382 on the control post 388. If the gun is actuated, byapplying the operating pressure to line 282 as aforesaid, point 188 andbracket 192 are carried downwardly, during which movement the post isenabled, by virtue of the tapered surfaces 322, to forcibly retractdetent 318. Detent 318 thus does not interfere with closing movements ofthe gun. When the pressure in line 282 is released, the pressure inchamber 294 is enabled to separate the points, and thereby move post 388upwardly. This up- 7 Ward movement is limited by the engagement ofdetent 318 with the first shoulder encountered by the nose thereof inthe course of the upward movement of post 388. The gun is consequentlyenabled to open only to an extent suitable to enable the gun to be movedto the next welding point on the workpiece. Such an opening movement maybe of usual magnitude such for example, as one-quarter to one-half aninch, as will be understood. In case a wider point separation is desiredfor any reason the trigger 328 may be actuated to momentarily withdrawdetent 318. Such a momentary withdrawal enables a separating movementequal to the distance between successive shoulders 382. If a fullseparating movement is desired, trigger 328 may be actuated to holddetent 318 in the retracted position until such movement is completed.It will be appreciated that the provision of the plurality of steps 382accommodates the structure to points 188-182 of various lengths.

"pose.

Any suitable "means may of course be utilized' tocontrolthe closing ofthe gun and the firing of the associated weldingcircuit. As shown, apush button operated dual switch "330 of a commercially availabletype'is utilized for this pur- Switch 3331s secured to-the handlecasting 254 by'means of studs 332-which pass through a bracket 334formed thereon, and are tapped into the switch housing. "Switch "330comprises a manually depressible button 335, which actuates a walkingbeam 338, which acts against a pair of vertically spaced spring biasedswitch operators 340 and 342. Ihe button 336 engages the beam 338"at apoint which is nearer switch operator 342 than switch operator 340.'When the button is depressed accordingly the switch elementsassociatedwith operator 342 are closed first. When closed operator 342 forms afulcrum point for beamv 338. Continued button movement consequentlydepresses operator 34B and crosses the corresponding switch elements. Aswill be understood, the closure of switch operator 342 may be-utilizedto effect the closing of the gun and closure of switch operator 340 maybe utilized to actuate the hereinafter described contactor and initiatethe flow of welding current.

Referring now to Figures 4, and 11, con-- tactor H4 is illustrated asbeing of the carbon pile type, employing carbon'elements which aredisposed to be separated to interrupt the circuit through the contactorand which are disposed to be pressed together to complete the circuitthrough the contactor. A very important feature ofthe presentinventionresides in'the provision of simple means for applying the pressure tothe carbons in such relation as to build up the pressure after initialcontact therebetween, and to reduce the pressure prior to separationthereof, at controlled rates, so as to provide proper control of theWelding current cycle.

More particularly, the contactor comprises a carbon pile assemblycomposed, as shown, of only a single pair of circular carbon discs 350and 352, which are detachably secured respectively, by means ofcooperating circumferentially distributed series of clips 354 and 356,to the previously mentioned cooperating terminal members I I2 and H6which'may be and preferaly are formed of copper or other highlyconductive :material.

The lower terminal member I I6, which is .circularin shape, but isprovided with a radially projecting connecting portion 358, forconnection to "the previousl mentioned flexible shunt H8 (Figure 4), isrigidly secured, by means of a plurality of circumferentiallydistributed studs36il, to .a relatively heavy base plate 362. Base plate362 in turn is secured, through mounting blocks 364 (which may andpreferably do incorporate rubber pads or other resilient elements, notshown) to a pair of channel members 366 which are welded toandextend'between two upper cross members"! of'the frame structure. Anenclosing hood 368 may be and preferably is seated over the top of theframe structure to form an enclosing housing for the contactor. The hood368is provided with a plurality "of grilled ventilating openings 310,which, in-cooperation with other openings which may be provided in theside doors 80, and .inthe under side of the frame structure (see centralopening 312) afiord an adequate circulation of air throughthe entirepower unit.

The .lower terminal member H6 is insulated from the aforesaid basemember 362, as by insulators 314, 316, and 318.

The upper terminal member H2, also of generally circular 'form, having aradially projecting connecting portion'380 for cooperation with thepreviousl mentioned flexible shunt I I0, is rigidly secured to apressureplate-382, by means of a circumferentially distributed series of studs334. Members H2 and 382 are insulated from each other by means ofinsulators'tdt, 388, and 396.

.Carbons35ll and352 are shown in a position of initial engagement witheach other, but arecontinuously urged to a position in spaced relationto each other, .by a circumferentially distributed series of springs363, the upper ends whereof are seated over bosses 392 which projectdownwardly iroma corresponding series of radial projections 3J4 formedon the upper terminal member H2. Springs 336 are guided in verticalpassages 396 provided therefor in the lower terminal member Hi3, and thelower ends thereof bear against adlusting studs 368. The passages 396receive insulating sleeves 4'30 and the lower ends of the springs areprovided with insulatin fittings 432. It will be appreciated thereforethat springs 33% do not afford an electrical connection between theterminalmembers H2 and H6.

The operating .mechanism for the contactor comprises a ram 4H1, thecylinder whereof is constituted by upper and lower portions 4 I 2 and 4I4, which are secured together by means of a plurality ofcircumferentially distributed studs H6. The under side of the low-ercylinder portion 4l4, rests upon a plurality of spacing sleeves 4 I 8,which are interposed between cylinder portion I4 and the bottom plate362. A plurality of studs 420 pass'through the flange 422 of the lowercylinder portion 4 t4, throughthe sleeves M8, and through acorresponding plurality of openings provided thereforin radialenlargements 423 formed on the base plate "362. Studs 420 and spacers4i8 thus serve to rigidly-interconnect the ram 4N3 and the base plate362.

In order to maintain the upper carbon 350 and its terminal member H2 inproperly centered relation ,to'the lower carbon 352, the pressure plate382'is provided with apair of diametrically opposite radially extendingU-shaped projections 424 which loosely embrace a corresponding pair ofthe spacers M8.

The ram 4l0-.-is provided with a piston 436, which is verticallyslidable therein, and which is provided with a .piston-rod-like member432, which is slidably received in a guide opening 434 providedinthebase portion of the lower cylinder portion '4I4. .A compression spring436 isseated between theunderside of .the piston 43!! and the uppersurface of thejust-mentioned .base portion, andcontinuously urges thepiston to an upper limit position, in which its upper surface abuts the.under side of a downwardly-projecting boss 438. formed on the cylinder.cover.

Piston 43ll is provided with a downwardly projecting neck 446, whichpasses loosely through a central openingformedina downwardly presentingcircular, cup-like cam member l'42, the lower portion-of which defines.a conical cam surface 44.4. '.Cam..member 442 is heldin place betweenthe piston surface 446,.and a collar 448 which .i secured .to the pistonby a central. stud 450. Thus, while cam 442 may float to alimited degreein a .radialdirection.withrespect to piston 436, it'isifixed-in.placeaxially of the piston.

.The .base of the. lower cylinder portion M4, is cored or otherwiseformed to define a plurality of generally rectangular openings 452,threebeing shown. Each opening has associatedwith it a pair of bearingbosses 454 which may be and preferably are cast integrally with the baseportion of the ylinder portion 454. The respective pairs of bosses 454receive trunnions 456, which serve as pivotal supports for pressuremembers 458 which, functionally, are bell-crank in nature. The upperends of the bell-cranks 458 are bifurcated to define spaced legs 460,which receive between them grooved rollers 462. Rollers 462 are carriedby ins 484, which are supported by the legs 468. The under side of eachbell-crank 458 is provided with a vertically extending pin receivingrecess 464, the base 466 whereof is spheroidal and forms a socket toreceive the correspondingly shaped upper end of a corresponding pressurepin 468. The base 410 of each pressure pin rests freely upon the uppersurface of the previously-mentioned pressure plate 882.

With the just-mentioned arrangement, it will be appreciated thatpressure is transmitted from the piston 480 to the pressure plate 382,through the three symmetrically arranged bell-cranks 458, it beingappreciated that one pressure multiplication is afforded by the cam orwedge-like conneotion between rollers 462 and the cam member 442, andthat a second pressure multiplication is afiorded by virtue of therelatively short horizontal distance between the centers of pins 468 andtrunnions 456, as compared to the relatively long spacing between thecenters of pins 456 and 464. Accordingly, utilizing air pressures ofusual magnitudes, approximately 90 pounds, and without requiring anunduly large piston area, extremely high pressures, of the order of100,000 pounds, can be applied between the carbons 350 and 352.

Before describing the overall operation of the system, reference is madeto Figure 7, which shows a diagrammatic layout of air circuits which maybe used in the practice of the invention. In this figure, air issupplied from any suitable source 410 to a main header 412. It is withinthe purview of the invention to carry the source 410 on the truck 26, inwhich event the storage batteries may also afford a convenient source ofenergy for the driving motor associated with the usual air compressor.Alternatively, of course, the compressor may be located remotely fromthe truck 26, and may be releasably coupled to the header 410, as by aconnector 414. Header 410 is provided, in the illustrated instance, withfour branch lines 416, 418, 488, and 482 which lead, through usualreducing or pressure regulating valves 484, and past gauges 486 to thepreviously mentioned reservoirs which are constituted by the framemembers of the power unit and which are correspondingly designated inFigure 7. One of the reservoirs 12 leads, through a conventionalthree-way valve 488, and line 490 to the inlet connection for thecontactor I I4. As will be understood, valve 488 normally isolates itsreservoir 12 from the contactor I I4, and connects the latter toexhaust. Upon being actuated, which may be accomplishedelectro-magnetically, valve 488 closes off the exhaust connection andconnects contactor I M to its reservoir 12. As is indicated by thelegend in Figure 7, valve 488 may be and preferably is actuated by theswitch 340 associated with the welding gun 22, a portion only of whichis shown in Figure 7.

The other reservoir 12 is continuously connected by thepreviously-mentioned line 288 with the chamber space 284 within the gun22 and so serves to normally maintain the gun in either a partially orentirely open position, depending upon the condition of the control post300 associated with the gun. Line 288 carries a relatively low pressure,just sufficient for retracting and point dressing purposes.

The remaining two reservoirs 10-14 are connected by lines 492, 494, and496, with the previously-mentioned line 282, through which air isadmitted for actuating the gun. Line 282 contains a, three-way valve498, having the operating characteristics described above in connectionwith valve 488, and which, as is indicated by the legend, is disposed tobe actuated by switch 342 associated with gun 22.

Line 492 contains a usual check valve 500, which permits air flow inonly the direction indicated by the arrow and lines 494 and 496 containusual two-way valves 502 and 504. The reservoir 10-14 associated withcheck valve 560 carries a lower pressure than does the other reservoirilk-14, which pressure is however substantially in excess of thatprovided by the reservoir 12 associated with line 288. The reservoirs10-14 and their associated connections thus permit operation of the gunat either of two initially predeterminable pressures. For example, byopening both of valves 502 and 504, the pressure in line 494 is madeavailable to line 282. By closing valve 584, leaving valve 502 open, thepressure in line 492 is made available to line 282. For point dressingoperations, both of valves 502 and 884 may be closed (which of course,may be either manually or automatically effected) whereby the pressurein the reservoir 12 (associated with line 288) is made vailable to line282, through line 506, which contains a check valve 508. As previouslymentioned, this reservoir 12 contains air at a pressure too low foroperating purposes, but suitable for point dressing purposes. Under theindicated conditions, both of lines 282 and 288 are supplied at the samepressure. By reference to Figure 8, however, it will be noticed that thepressure in line 288 acts against a larger effective piston area thandoes the pressure in line 282, and so is enabled to cause the gun toclose with a relatively low pressure between the welding points.

As will be understood, the various regulating valves and gauges may beand preferably are carried at the front of the frame structure of thepower unit 20, so as to be readily accessible to the operator of thesystem. No attempt has been made, except in the diagrammatic showing,Figure 7, to illustrate the arrangement of the piping in unit 20, exceptto indicate where the piping may be connected into the frame reservoirs.It is noted that the previously-mentioned opening 312 in the base of theframe structure (Fig. 4) affords a convenient means for leading in theair line from the pressure source 410. Such opening also affords aconvenient means for bringing in the charging connection from therectifier, the terminals of which charging source may of course bedirectly connected to the positive and negative bus-bars 96 and 98, andwhich air and charging connections may incorporate slip-ring orequivalent instrumentalities to permit an unlimited pivotal movement ofthe power unit 20 relative to the truck 26. If it is desired to limitsuch rotation of the power unit to less than 360 degrees, it will beappreciated that the just-mentioned slip-ring connections may beomitted. In Figure 2, cooperating stops 21 and 29 carried respectivelyby units 20 and 26 cooperate to limit the swiveling of the unit 20 toapproximately 360 degrees.

As to operationofxthesystem as a whole, it is believed that theoperations of operatin the truck '26 willbe evident from the previousdescription. Similarly, it is believed to be evident thatthe:rheostatconnection associated with the bus-barand hangerstructure-24 may be adjusted, .by releasing the handle !'T4,.so as tointerpose a desired amount of resistance into the welding circuitytoaccommodate "the work to be Welded. Under normal circumstances, also,gun 22 may 'be regarded as occupying the fully opened posi tion shown inFigure 8, under the influence of the pressure in its chamber space 294.

"In'order'to make a'weld, and assuming that "the work has beenintroduced between the gun points -l80-and IBLthESWitCh button 336 onthe :gun may be depressed in a single continuous -movement. At anintermediate stage of this *movement,-by'virtue of the unbalanced pointat whichthe button acts against the walking beam 338, switch'342 isclosed. Through usual circuits (not shown) such action energizes valve498 associated withqgun 22 -Figure 7). Upon being energized, valve 498connects chambers 284 and 28,6 of gun.22 to one or the other of thereservoirs 10l4, depending upon the condition of control valve 504. Thisaction causes the gun points to promptly close against the work at aproper welding pressure. Shortly after the gun points close, whichaction may be expected to take place faster than the depressing movementof button 336, the latter reaches its inner limit position and closesswitch 340. The latter action energizes valve 438 through conventionalcircuits (not shown) and admits air to ram 4|0. Under the normal conditions, as aforesaid, piston 430 is normally in its upper limit position,as influenced by sprin 435, and the upper carbon 350 is spaced above thelower carbon 352, as influenced by the series of springs 390. As the airpressure builds up within the ram M0, piston 43!! is forced downwardlyagainst the force of spring 436. This movement carries cam 442downwardly past the three rollers 462, and forces the latter to moveradially outwardly. This movement is communicated to the upper terminalmember I I2, and causes the latter to move downwardly and bring thecarbons 350 and 352 into engagement with each other. This actioncompletes the welding circuit and enables the batteries to supplycurrent through the previously described connections, to the weldinggun. The just-mentioned initial engagement of the carbons takes place atan intermediate value of air pressure in ram 4 i 0, by virtue of thetime delay necessarily present in the build-up of such air pressure tothe value established by its reservoir 12. This rate of build-up may, ofcourse, be regulated by interposing a suitable regulating valve in thecontactor air line, such a valve being indicated diagrammatically at50!. As the pressure in ram 4H1 builds up from the initial contactorclosing value to the reservoir value, the downward movement of piston430 tends to continue but may be expected to do so to only a negligiblysmall degree. The increase in pressure does however proportionatelyincrease the pressure between the carbons, which increase in pressure isaccompanied by a corresponding reduction in the electrical resistance ofthese elements. When the pressure attains the reservoir value, theelectrical resistance of the circuit is at a minimum, so far as isdetermined by the contactor, and is of a value determined by the slidesetting of the hanger and bus-bar 24.

It will be noted that under the conditions the gun. the welding of.virtually all types of materials,

' stated,:the electrical resistance :ofthe circuit as and, withoutrequiring an unduly large number of batteries,.may deliver currentdensities of the order of. 30,000 amperes.

;As will .beunderstood, the actuation of valves 183 and 408 in responseto closure of button..-336 are normally accomplished through theintermediary .of a usual welding timer, which serves to doenergize inproper sequence, both of valves Q andMlB, at the expirationof-aninterval suited to the welding operation.

The de-energizationsof valve4t0 vents ram 4-l0 to atmosphere, therebyenabling the separation of the carbons 350and 352, which actioninterrupts the welding circuit. The rate of decayof pressure in ram 4|.0maybe controlled by the previously-mentioned regulating valve 50! or byother suitable means. It is usually found that a substantially freeescape of air from ram M0 is satisfactory. It will be understood thatthe decay of pressure in ram M0 causes a corresponding decay of pressurebetween the carbons, before the latter elements actually separate. It ispreferred to so regulate this decay of pressure as to give the weldingcurrent time to fall away to a value which is a minor fraction of themaximum value before the carbons actually separate. The inductance ofthe present welding circuit as a whole is exceedingly low. The rate ofdecay of welding current, caused by the decrease in pressure between thecarbons is consequently very rapid. By virtue of this fact, it isusually satisfactory, as noted above, to permit a substantiallyunimpeded escape of air from the ram 4H) and still attain the desiredminimum current value before the carbons separate. As an example, andutilizing a maximum current of the order of 25,000 amperes, it ispreferred to delay the separation of the carbons until the weldingcurrent has fallen to a value of the order of 1,000 amperes.

Shortly after the de-enerigization of valve 488 and the interruption ofcurrent through the contactor, valve 498 is de-energized and enables thepressure on the gun chamber 294 to separate the points, the degree ofseparation being overned by post 300, and being, preferably, justsufficient to allow the gun to be readily advanced to the next welding.point. If, as previously described, a wider or complete separation ofthe points is desired, trigger 320 may be withdrawn thereby releasingdetent 3 l 0 from post 300.

It will be appreciated that although, in order to simplify the drawings,water cooling connections have not been shown or described in detail, itis preferred to supplement the gun cooling connections indicated inFigure 8, with water cooling connections associated with the upper andlower contactor terminals H2 and H6, with the busbars 06 and 08, andwith the battery connectors 94. It is within the purview of the presentinvention to provide the truck 26 with a source of s-uffi cient coolantfor these cooling circuits, power for the driving means wherefor may bederived from the batteries. Usually, however, adequate sources .ofcoolant are available and may be led to the system in conventionalfashion.

[movement with respect thereto, said hanger in- Although only a singlespecific embodiment of the invention has been described in detail, itwill be appreciated that various modifications in the form, number, andarrangement of the parts may be made without departing from the spiritand scope of the invention.

What is claimed is:

1. In a welding system, a portable welder, a hanger for mechanicallysupporting the welder, said hanger including bus-bar means through whichpower is delivered to the welder, means forming an adjustable supportingconnection between the welder and the hanger, and flexible conductormeans for electrically connecting the welder to the hanger.

2. In a welder, a frame structure, power means carried by the framestructure, a hanger pivotally connected to the frame structure, aportable welding gun carried by the hanger for universal eluding bus-barmeans through which .power is delivered from the power means to thewelding gun, and flexible electrical connections between the gun and thebus-bar means.

CI ESTER F. LEATHERS.

16 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Number Name Date Woodrow May 15, 1916Cushing et a1 Mar. 16, 1926 Leswlnka. Oct. 18, 1927 Meadowcroft Apr. 3,1928 Von Henke Aug. 6, 1929 Meadowcroft Oct. 25, 1932 Platz Apr. 10,1934 Eckman July 5, 1938 Martin Aug. 9, 1938 Watkin Sept. 20, 1938 PlatzOct. 24, 1939 Jardine et a1 Feb. 27, 1940 Leathers -1 Sept. 22, 1942Thacker Dec. 15, 1942 Berriman Sept. 28, 1943 FOREIGN PATENTS CountryDate France Feb. 15, 1937

